Switch



Jan. 14, 1941. P s BEAR 'E1-AL 2,228,251

swncn original Filed June 1e, 1937 s sheets-sheet 2 Jan. 14, 1941. P, Q BEAR ErAL .y 2,228,251

SWITCH Original Filed June 18, 1937 3 Sheets-Sheet 5 Patented Jan. 14, 1941 UNITED STATES PATENT OFFICE 2,228,251 swrron poration of Indiana Application June 18, 1937, Serial No. 148,946

. Renewed December 31, 1938 13 Claims.

This invention relates to mercury switches, and more particularly to such Switches of the metallic envelope type as disclosed generally in our copending application, Serial No. 745,842,

nled September 28, 1934. Briefly, the present invention is directed to switches using a metallic envelope as one electrode, with an open end in which is disposed a ceramic insert supporting a second electrode disc and forming therewith a mercury retaining recess, with suitable compression and sealing means in the end of the envelope.

Certain problems have arisen in connection with the commercial development and applical5 tion of such switches to the solution of which the present invention is directed.- One such problem has been the demand for quick acting small capacity switchesv used in sign ilashers, and in controls for feed mechanisms where the switch I is employed to make and break a circuit many times a minute.

In overcoming' the problems arising in the use of such switches we have made certain advances in switch design and construction looking to- 2l ward the dissipation of heat from the interior of the switch when in high speed operation, the g control of the movable contacter to accommodate it to the required type of operation, and various modiilcatons and rennements in the seal- N ing of the open end of the envelope and improvements in the switch parts to provide an economical, simple and rugged switch of the metal en- VDDC type- We have found that the use of a compression 35 disc of a moulded condensation product, such as Bakelite or the like, has several disadvantages when disposed in abutment against the resilient cushioning means which seals the electrode and the outer end of the ceramic insert and which is n compressed axially into sealing position. The

heat built up imder repeated high speed opera.- tions causes the electrode to become heated, and this heat is transferred through the resilient sealing means to the laminated compression disc. i5 This heat and pressure on the disc causes it to reform in a dished or frusto-conical form, opening up the seal and rendering the switch inoperative. This has been found to occur, even though the compression disc is supposedly not yieldable 50 or reformabie. Since we employ a partial liquid fill in such switches, the reforming of vthe disc allows the electrode stud to unseat, whereupon the liquid i111 contactsthe sealing means,vwhich in ,some forms of the switch may be of rubber, and produces a sticky mass which causes the switch to blow up. Another .disadvantage in such Switch structures resided in the fact that under heavy loads there was a tendency for a flashover across the surface of the disc between the shell and the electrode stud. This produced a 5 carbonized path along this surface whichsoon rendered the switch inoperative. One object of the present invention is to provide a switch construction of this type employing as a compression disc a material that is not 10 thermo-plastic, is a good heat conductor, and which will withstand high compressivev stresses. Thus the disc will not yield or deform under heat and pressure, will dissipate heat kfrom the electrode stud and from the resilient sealing means, and will be able to receive and transmit to the rubber the compressive stresses necessary to effect a proper seal. We have found that a ceramic material known commercially as Isolantite possesses all these characteristics and is of further advantage in that a flash-over across its surface will not deposit; a carbonized path which tends to destroy the switch in a short time. The ceramic thus dissipates the heat from the resilient Sealing means at a rate such that no deleterious action occurs in the seal, prolonging the effective life of the sealing means.

Another disadvantage in previous switches of this type vhas been the fragility of the ceramic insert forming the support for the internal electrode. Heretofore such inserts were formed with a long tapered raceway in order to provide a low operating angle for the switch. This produced a thin section which was easily broken or chipped. Also, the recess in the ceramic which forms, with the electrode, the mercury-retaining recess, had a relatively vthin wall section, and under heavy loads tended to flash-over between the retained body of mercury and the shell or envelope. The annular cylindrical lip or shoulder also was disadvantageous, since the inserts are moulded, and the formation and drawing of such a shoulder was extremely dimcult in the mold without chipping and cracking.

The present invention contemplates the provision of a ceramic ci such design and thickness as to eliminate the possibility of flash-overs between the retained body and the Surrounding shell, and provides a tapered shoulder which is much easier to form and which facilitates and increases the effectiveness of the sealing means. At the same time the long tapered raceway has been eliminated, reducing to a minimum any possibility of damage to the insert in its forming and assembly. We have found that the operating angle can be controlled emciently without such a raceway.

In this connection we have found that a ceramic commercially known as Alundum is especially adaptable for use in this connection. It is a relatively poor conductor of heat butuis highly refractory and is not'biecten etched by an anhydrous alkaline licuid fill such as we employ and which is described in detail'in our copending application, Serial No. 745,842, filed September 28, 1934. This ability to withstand'v etching under electric arcing and high temperatures when used in a switchhofthis isof distinct advantage. Also, material has mail terially less shrink than porcelain or other types of ceramic heretofore used, and hence can'be formed within relatively close limitsff Another advantage obtained by th present in'""` vention resides in the use of a ceramic compression disc of the Isolanti type. which nts about the shank of the velectrode and which has an inwardly directed tapered' or wedgelikle shoulder terminating against 'the 'iaceof the felectrode. Since this materiall is a 'good conductor 'of heat, it transmits the'heat fromthe metallic electrode directly, without passingthisiieat'thrugh the resilient sealing'means. Also,`vsince' itis not reformable under heat and 'pressure it Y'prevents 'the sealing*A means 'from gettingr around the edge cf the electrode mic contact with the liquid nii. The tapered shoulder produces a' radial component of pressure on thefseai and also giving a good seal at the'outer face o f'the electrode about itsxpeyripherm(I A Another feature of the present invention resides in the manner in'l'which the conductor leads are embedded in the end of the We have used compounds or cements of a cellulose acetate cement mixedwith neiy'ground 'marble dust tc' cmbed'thciecds in Vthe end of the switch, thislmctcrlal being applicati pacte ferm and settinginto a hard cement# Howevernthis compound, .commercially v known as green dip cannot be entirely ofi'seteven' with lthe granules of marble dust therein, andualso is nottemperature-resistant narrate? resistant; slowly combustible at, kipdlmg temperatures. sucn. a

'compound doeskeep the leads ilrinlyembeddd, y however, and relieves the strain onthe soldered or. lug connections to' the envelope` and 'stud when tension is4 applied thereto, 'Ihe compound is advantageous in that it ma'ybe, employed to oement the switch envelope' to the interior oithe mouldedoutervenclosing case, and to cementthe mouldedend cap to the case enclose the switch. h'bldng Phe DSM. .firmly meth?? to liclobe switch; ompietelywithlnf a moulded1 insulati ng ease' f j l.. ,-A`,I- n y. ,.Hj l 'n .1n placed: thecellulssltstc cement we 'may also use', 'afjcompciindfknwn commercially as j Porcelute which consists of 'a ceramicpaste oar.

ried in a silicate binder. This materialhas great dielectric strength, is heat water .resitntfsnd is alsof thermally, conductive-- Whenitfhas; set lt forms aneven better-em vbedlnrllt oi the leads, and adheres iirmly to other ceramics; and i must be chipped away .in small 70.

fragments iiorder be removed. By using this 'material we rind that :lo special lugs or terminal clips need be employed, and direct soideredconnections' to the shelland thestud may be made..

" However-,the material does not adhere to Bakelite" or similar moulded' condensation products,

assenti once setting. By using a ceramic compression'dischaving an end recess about the stud, the lead may be coiled about the stud within this recessffand the Ventire end of the disc, stud and "the adjacent portion of the lead may then be enclosed in this cement, forming an ideal end seal. The cap member may then be secured to theend o! the enclosing case-withthe usual rubber cement, forming an effective water-prooi seal about the leads andbetween the meeng edges of the end cap and enclosing shell. With rubber covered leads this forms an ,entirely waterproof switch closure. e

Another feature of the present invention is the provision of a switch stnicturein which the resilient sealing means is maintained at a uniform temperature on both surfaces by employing heat conductingmeans in abutment therewith. whereby the heat transmitted to' one side ot the seal is transmitted therefrom at the same rate. maintaining the body of the sealing means at a uniform temperature. In one form of the invention this object is attained by employing ceramic heat conducting memberson opposite sides of the resilient seal which act uniform heat dissipators.

Still another object of the present invention is Athe provision, in a switch of this type employing Alundum as the ceramic electrode supporting o! plurality of neat" conducidos un .roldissioating'the heat rapidly am n@ che sharocuttins edseatwhicharccmybcmated'. Since .Alundum is in itself n poor ecnductor oi' heat, this prevents localised heating and insuresaoooioperatingswitchevenunderhigh 'speed operation.

In order to' control, in switches or uns' type.

'thespeedatwhichtheycanbeopermwepreferably provide for varying the viscosity ot the anhydrous alkaline liquid iilm which enolos f the movable mercury contactor and the retained mercury. In a form of the invention this nlm comprises triethanolamlne. We have found that the viscosity 'ci this mate rial, which in itself is a tough, visoous'iiim-form- 1 ing substance, can be varied within a the, addition o! alcohol thereto, the viscosity varying almostdirectlyin accordance with the amount of alcohol added to the illl. 'Ihm for highspeedoperatiomtheflllisthinnedoutwith alcohol to decrease its viscosity. allowing the mercury to move faster and thus reduce theV time 'required betweensucoessive switch operations. lF.Ilievoperating angle of the switch can also be.

controlled to some extent by controlling the viscosity ofthe liquid n11. N

' lWe may, if desired in' order to obtainhigh sneed switch operations, employ the inertia e!- fect oi the mercury for making and breaking contact, instead of tilting the switch. In other words, by moving the switch horizontally at high speed, the inclined raceway is driven like a wedge under the body of mercury. which remains more or less stationary due to its inertia, thus raising l this mercury into contact with the retained body.

Similarly, by reversing the movement of the switch body, the wedge is drawn out from under the main body of mercury, causing it to drop away'irom the retained body to break the circuit. Either mechanical, electrical or hydraulic means may be employed for imparting this high speed oscillation to the switch envelope.

Under such conditions of high speed operation,

the switch makes and breaks contact many times per minute, and consequently the thermal conduction attained as heretofore described is essential in order to maintain the switch operating temperature within reasonable limits. This can be effected by using thermally conductive ceramics on opposite sides of the resilient sealing' means, and by providing a plurality of heat dissipating paths froml the point of heat generation to the external portions of the switch.

In place of the conventional spring clips formerly used to mount mercury switches upon operating mechanisms such as heat, level or pressure responsive devices, or on oscillating and reciprocating mechanisms, we have foimd that switches of the type provided by the present invention `are peculiarly adapted for bracket mounting by means of brackets threaded or secured to the protruding shank of the electrode,

and a further object of our invention is to provide a switch structure having this type of bracket support.

Still another feature of our invention resides in the provision of a structure whereby the switch leads may be brought out of the enclosing insulating case at any desired angle. either together or circumferentially spaced. This is attained by a novel type of enclosing shell having 0 an end cap cooperating with the end flange of Y the shell to 'secure this adiustability of lead position andl which is adapted for completely enclosing the switch structure per se. This, in combination with the cementing of the leads in embedded relation at the switch end,

provides a switch which is waterproof and operable under water or oil, and which at the same` time provides a decorative appearance highly desirable in installations where the switches are visible. l

Other objects and advantages of the present 'invention will be more apparent from the fol-A lowing detailed description which, taken in conjunction with the accompanying drawings, will 5l disclose to those skilled in the art the particular construction and operation of preferred forms of the present invention.

In the drawings: v Figure l is a vertical sectional view of a switch 00 of the present invention;I

Figure 2 is an enlarged corresponding view of .a switch of smaller capacity;

Figure 3 is a similarly enlarged view of a switch of intermediate capacity;

Figure 4 is a sectional view through'a switch having a modified end seal construction;

Figure 5 is a similar view of a further modification of the end construction; Y' Figure 6 is an exploded perspective view of the enclosing shell and cap;

" Figure '1 is a diagrammatic view illustrating the heat relationships of one form of the present type of switch;

Il Figure 8 is a sectional view of a mechanical reciprocating mechanism for high speed operation:

Flgure9isaviewsimilarto1i`igure8showing another position in the operation of the mechanism; e 5

Figure 10 is a somewhat atic view of an electrically controlled reciprocating mechanism; and

Figure 11 is a view, partly in section, of a moimting construction for vswitches of the presl0 ent type.

Referring nowin detail to the drawings, in Figure 1 we provide a switch comprising the metallic cup-shaped envelope ID having the enlarged operiA end I2 joined to the main body por- 15 tion of the envelope through a frusto-conical section I3. Within the open end of the envelope we provide the ceramic insert Il which may be formed of any moulded refractory, although we preferably employ a ceramic commercially known 20 asrlsolantite, or for certain installations` we may employ a ceramic known commercially as Alundum. The particular characteristics of y these two types of ceramic will be described in detail hereinafter. 25

The ceramic Il has a tapered frusta-conical surface fitting within the section I3 of the envelope, and is provided with the internal tapered throat or runway i5 leading to the radial shoulv der I6, there being a sharp cutting edge dening 30 the intersection between the runway and the shoulder.

'I'he ceramic has a rearwardly extending cylindrical ange portion I1 of a slightly larger internal diameter than the diameter of the annular 35 surface I8 which is adapted to receive the electrode disc I9 seating against the radial shoulder between the, surface I8 and the internal annular I surface of the flange I1. The face of the electrode I9 with the surfaces I6 and I8. is adapted. 40 to denne a mercury retaining groove or recess of a dimension such'as to maintain therein a stable body of mercury, indicated at 2li. The particular dimensional relationships of the portions of the structure forming this recess are 45 clearly set forth in the copending application, Serial No. 53,146, filed December 6, 1935 now Patent No. 2,132,921, issued October 11, 1938.V

The body of mercury 20 is in continuous con-- `tact with the face of the electrode I5, and is.50

adapted to be contacted for closing a circuit through the switch by the movable mercin'y contactor 22 carried within the envelope I0, and mov-l able up the runway I5 upon tilting of the switch. We preferably provideV a liquid ll of an anhy- 55 drous alkaline type, and preferably of the class of triethanolamine, which normally is a tough viscous liquid which forms a lm over the mercury and prevents oxidation thereof, while at the same time increasing the normal meniscus height of the 60 mercury as disclosed in detail in our copending application, rst above-mentioned.

In order to effectively seal the interior of the envelope and the ceramic, we provide resilient sealing means such as indicated at 23 which may 65 be formed of synthetic rubbernr of any other suitable sealing material having a peripheral flange portion 2l which projects into the annular space betweentheiiange IIandtheinterloroftheem' larged and I2 of the envelope. The radial portion 70 of the sealing means 23 seals the end surfaceof the flange I1 and the rear face of the electrode Il about the electrode shank 25. Y

To compress the sealing means into sealing engagement with the respecve surfaces, we provideinthepresent embodiment ci the invention a ceramic compression disc 2l preferably of'the Iso1antite"which is on 'its outer facci by .the terminalug washer ijf andtlie amni- 1er compression ring u.A The disc is forced "ially againsrthe sealingmeans' I3.v

`By'employng a ceramic compression disc', we obvlate thedisadvantages formerly :found in switchesv of this type which Bakelite ora similar moulded condensation product was em'- ployed for lthecolnpre'ssion 'ineansxWhile Bakerlite is'rnot supposedly eformable-undr heat and pressure, we' found that under-the pressin-es obwould reform into a concave shape allowing un- -seating f the electrodewhich; lnt'urn," would allow the sealing means to come inconta'ct withrthe "'liquidii-li of the envelope, 'rendering the sealing ineens'ineffective.` `=0omprc`ssiondiscsof the former type werel also objectionable because of the fact that they didin'ot act `as good thermal conductors, and consequently prevented dissipation 'o'f heat from lthe sealing means 23 vso that the heat transmitted thereto from the 'insert il and'through .the Velectrode S due to arclg within the switch remained in the sealing-means, raising its temperature to a'point such that Vit rapidly deteriorated and lost its characteristics.

Also, any ilashovers aicross the 'surface of the prior of compression lnfdepositinga carbonined path over the surface which immediately'reduced the dielectric capacity of the member, and in a short timeresultcdln 4failure of the switch under any appreciable"`loads. With the ceramic type of compressionfme'anathe -h'e'at dissipation from the sealing means is substantially equal-to the transfer of heat thereto" so that both sides ofthe sealing means remain at substantially uniform temperatures. Further, the ceramic being thermo-plastic, it will not be reformed under heat or pressure, and thus will retain its planar shape throughout the life of the switch. In addition, any dash-over across its surface will not produce a carbonized path so that the dielectric strength of .the compression disc is maintained at all times.

Disposed outwardly of the compression disc 2l we provide a ceramic insulating spacer Il about the electrode shank 2l which serves as an axial spacing member for the conductor leads 32 and Il connected respectively to the terminal lug washer 21 and tothe terminal lug Il secured to 'the end of the electrode shank by the nut We also may employ an insulating spacer disc Il which may be formed of any suitable insulating material and which serves as a radial spacing means between the conductor leads. The switch h'detaiiinconn" v'them so thatV anys tension'fuponthe leads -wiil not resultin diseonnectioirof the leads from their terminal connecten' we' preferably provide an'A vksealing Ic'onipouxni or -oement `indicated :generally at in '1; This compound may be of the :"green dip" comprising a cellulose acetatebase'cemmt; -into which is mixed ilhe iihelygmund'marble-'dust for purposeof shrinkage vonl drying and to'prevent the formation Voff-large voids or "pocketsiin 'the cement. This materiali is slowly combustible, but has good insulating .diaracteristics ands'erves fas an embedmentYOr-'the leads, -taking the strain of Vof the soldered* connections of the leadsto' the yterminal-lugat IThis'material is preferably vapplied to--thef the end 2l of the envelopeand the insulating'spacing disc Il by'mea'ns'ofa spatula-fand itvmay also preferably be usedin the 42 'between the end cap I8 andthe insulating spacing disc Il..

'I'he material has the capacity to cement the end cap 38 to .the member II to hold the members together in order tofenclose the switch. The use of a cement off this type provides for embedment of the leads, and also serves-.tomi .the space within the interior of the members 3i Il.

However, w'e und thatin order ic' better insulating qualities, it may be desirableto employ in the space 4l a material commercially known 'as Poroelutef which* is fa cement :consisting of kaolin-mixed within-'silicate hindert' and which -has` relatively little` shrinkage upon settilsig.` -This material is thermally conductive, butlias high dielectric strength andisrefractory in fcliaracter. Howevenit -wili v--not I'a-rment for the parts and ,and if used inf'the space 4I. the gree`dlp" must stili be ul'edto cemeiifthe end cap Il to the case member I8. 'I'hinanner in whlch'we-prefer to close the end ofl the switch will in de'tailin connection with Figure 5, although either of themcthods-'thus far described may be employedif desired f1 The of the 'ceramic compression'disc 2l 4andthe-ceramic `spacer" v'is on distinct value insofar as dissipation of heat is concerned, and also in providing for high electrical insulation between the electrodes of the switch. Further. not being reformable under heat or pressure, these members maintain the electrodes in Dosition, and also provide for retaining the desired compression upon the resilient sealing means.

Considering now the details of the switch construction shown in Figure 2 in which we provide a switch of a relatively small capacity such as of the order of one ampere, we provide an envelope Il which may be formed of suitable stock having an axial bore l2 and an outer counterbored portion Il forming therebetween a shoulder Il anint which a ceramic insert Il is engaged. This ceramic insert is preferably of the type having high thermal conductivity while still being resistant to heating due to arcs within the switch. Within the interior of the envelope we provide a movable contactar Il which is adapted to make and break contact with the projecting portion of an electrode l1 extending centrally through the insert Il and held against inward movement by s shoulder portion Il bearing against the outer face of the insert. Suitable resilient sealing means liisdisposedagainsttherearfaoeofthe insert Il and about the shoulder Il. and is oom- 7l pressed into position by means of the ceramic compression member 60 which has a planar face portion engaging the rear face of the sealing means, and is also provided with a projecting portion i2 of reduced diameter forming an insulating radial spacer between the spun-over end 63 of the envelope 50 andythe shank 64 of the electrode. A suitable metallic compression ring Y,

65 is provided between thel spun-over edge 63 and the radial shoulder on the rear face of the compression member 60 to force the compression member axially inwardly along the counterbored portion 53 of the envelope, thereby compressing the sealing means 59 between the two radial faces .oi the ceramic members and 60. Suitable conductor leads 66 and 61 have their ends respectively soldered to the projecting end of the' electrode shank 64 and to the edge 63 of the envelope 50. These leads are extending outwardly through openings 68 in the enclosing case member 69 which may be formed of wood or of a moulded insulating material. 'I'he envelope l0 .may be press-fitted within the bore of the case member 69, and plastic cement of the type described in connection with the embodiment shown in Figure 1 may be introduced about' the opposite ends oi the switch as indicated at 1li, although this may be omitted if desired.

This switch provides a mercury to metal contact, but since the loads carried thereby are relatively small, no disadvantage is occasioned by this type of contact. We may, if desired, introduce a liquid ll into the interior of this switch, although we find that it isnot necessary, and for high speed operation we preferably do notl provide such a fill.

In this connection we may point out that the particular liquid fill which we employ is of a relatively viscous nature and has a tendency to slow down the movement of the mercury during tilt- Ling or reciprocation of the switch.' For this reason we may desire to control the speed of i. movement of the mercury by varying the viscosity of the fill. For this purpose we iind that suitable control over the viscosity may be obtained 'by adding. alcohol to the fill in the desired quantities to produce a proportionate reduction in the viscosity of the fill and thereby produce a corresponding increase in the speed or rate of movement of the mercury.

Considering now the switch structure shown in Figure -3 in which a relatively small switch of a capacity of five amperes or the like is disclosed, we provide a switch envelope 12 substantially of the type shown in Figure 1 but of smaller size, which is adapted to receive the ceramic insert 13 therein, this insert carrying the electrode 1l which projects into the interior of the envelope andis held against inward movement by a shoulder 15 formed thereon between the electrodehead and the outwardly projecting shank portion' 18. The rear face of theceramic and the shoulder 15 of the electrode are engaged by resilient sealing means 1'1 having a peripheral flange portion 1l which engages about the annular shoulder formed on the insert, and provides both a radial and axial seal for the insert and electrode. The sealing means 11 is compressed into sealing engagement by means of the ceramic compression disc 19 of the type described in connection with Figure 2 having the projecting spacing portion Il about the extending portion of the shank 10 for providing an insulating space betweenA the shank and the spun-over end 02 of the envelope 12. In connection with both Figures 2 and 3, it will be noted that the sealing means is compressed be-v tween opposite faces of ceramic members and these ceramic members are preferably each o! the type having relatively high thermal conductivity and high dielectric strength. Thus, the

heat transmitted to the sealing means by the electrode carrying ceramics is dissipatedtherefrom at substantially the same rate by the cornpression ceramics, thus maintaining the sealing means at a substantially uniform temperature 'on both faces thereof.

Within the envelope 12 we provide a movable mercury contacter 83 adapted to make and break circuit with the projecting portion of the electrode 15. It will be noted that the inner end of the insert 13 is recessed, as shown at ll, to provide for increasing the contacting surface vbetween the mercury and the electrode. However, the diameter of the electrode is such that the annular space between the electrode and the wall of the envelope is less in cross-sectional dimension than the meniscus height of the mercury so vthat there will be no opportimity for the mercury to become locked in engagement with the electrode. 'I'he switch is preferably enclosed by the'case pieces'SS and 86 in a manner similar to that described in connection with Figure 1, suitable cementing composition 81 being applied over the portion of the ceramic member 18 and within the end cap 86 to ill this space and to embed the conductor leads 8l and 89 against displacement. These leads are led out through suitable notches formed in the interengaging edges of the case pieces and 8l in a manner which will be described. in detail in connection with Figure 6.

Considering now the embodimentl of the invention disclosed in Figure 4, the structure shown in this embodiment comprises an envelope ll of' fractory in nature and not etched by an alkaline illl under electric arcing and high temperatures. This material has relatively little shrink in moulding, and can be formed within relatively close limits. It is commercially sold as Bakers alumina RA 518" and comprises aluminum oxide or a mixture of aluminum oxide and silica dioxide. The particular insert I is provided with a relatively short internal raceway and has a relatively thick section between the mercury retaining recess 9| and the adjacent wall of the envelope 9|. This prevents any possibility of a flash-over between the mercury l1 lin the recess and the wall of the envelope through the insert which was a defect formerly found in inserts having a relatively long runway, and wherein the cross-sectional area between the recess on the envelope was consid-` erably less than that provided in the present insert. It was formerly thought that a long runwaywas essential for producing a low operating z Athe shoulder portion of the rear'of the ceramic 75 fits between the annular tapered surface Ill and the interior-of the end |I2 of the envelope.

whereby axial compression of the sealing means produces a component of pressure due to this tapered surface, which increases the effectivenessof the seal. The sealing means is also provided with a tapered aperture Ill formed centrally thereof adapted to receive the forwardly 'extending tapered nose portion il! of a ceramic compression member lll, preferably formed of "Isolantiie having a high thermal conductivity.

The compression member |01 has the radial portion which is axially compressed against the rear face of the sealing means |03 lto force the ange thereof into the annular gap about the shoulder s3, and the tapered surface of the nose portion i also produces a radial component of pressureon the sealing means for increasing its eifectivehess as a seal about the electrode-face, and also against the inner periphery of the envelope. The ceramic itl is provided also with a cylindrical reduced extension |l8 which forms an annular insulating spacer about the Ashank |28 of the electrode to insulate the shank radially from the spun-over edge ill of the envelope.

The compression member ill is moved axially against the rear face of the electrode S8 and against the sealing means by the compression ring il! which is disposed beneath the spunover edge iid of the envelope. The terminal lead il? is connected to a terminal lug washer IM disposed between the compression ring and the rear face of the discpcrtion of the member |31. The conductor lead |15 is connected directly to the shank lili of 'the electrode by means of a soldered connection or the like. In order to embed the leads to resist tension stresses tending to disconnect the ends from the washer i|4 and the shanl: its, we preferably apply a plastic cement lit over the end oi the compression member and about the end of 'the switch in a generally hemispherical form, this material preferably comprising Porcelui-e, which adheres iirmly to the compression member |91 and also to the metallic compression ring H2, and has keying engagement at the insulation of the leads H3 and H5 to firmly embed them therein. This material. is quick drying, and is of the required dielectric strength to prevent any possibility of flash-over between the leads H3 and lli.

The switch envelope 90 is preferably enclosed within an insulating case member Hl conforming generally to the shape of the envelope and having the extending yend H8 projecting outwardly beyond the spun-over edge of the envelope. An end cap insulating member H8 is provided having the peripheral axial flange |20 rcbbeted into the llange il! and cemented thereto by means of a plastic cement such as green slip, which lllls the space between the cement H6 and the interior of the cap as indicated at Considering now Figure 6 in detail, it will be noted that the case member Hl has the enlarged end portion S23 which encloses the emerged end |8201' the switch envelope. The edge ||8 of `the portion |23 is provided with an axially extending notch portion |24 for the purpose of leading out a terminal conductor auch u the conductor III of Figure 4. The member ||`l is preferably formed of moulded Bakelite" or the like, and closely conforms to the external shape of the envelope 00. llhe end cap member III having the flange |24 is also provided with an axially directed notch |28 which is cut in beyond the rabbeted edge I2! which engages within the annular edge Hl of the member ill. It will be noted that the lip or edge |26 is provided with a series of notched-out portions |21 spaced at various angles from the notch |25. 'I'he purpose of the notches |21 is to provide for selectively disposing the cap member III in any desired angular relation with respect to the case member ill, any one of the series of notches |21 being disposed in alignment with the lead notch |24 in order to prevent interference with the conductor lead passing outwardly through the notch |24. Thus the cap member may be applied in any desired angular relation to the case member Hl, and the leads may be brought out in any angular relation, depending upon the position of the notches |24 and |25. For example, as shown in Figure 4, the leads may be brought out on opposite sides oi the case member when the notches |24 and |25 are so located or the leads may be brought out at the same point in the periphery of the case. as molested in Figure 3, in which the notches |24 and |25 would be disposed ln alignment. This allows positioning o! the leads in accordance with the desired installation of the switch, and to accommodate the switch to various installations without requiring any modification of the component parts thereof.

Considering now in detail Figure 7, whlchis a somewhat diagrammatic view of a portion of the structure shown in Figures 4 and 5, it will be remembered that the insert I4 is of a material having poor` heat conducting characteristics.

'Howeven the use of such a material is desired because of its high refractory nature and the fact that it will not be etched or otherwise directed by the presence of the alkaline fill under high temperatures and electric arcs. This preserves the acute cutting edge between the mercury retaining recess and the runway Si, insuring positive repeat performance of the switch, that is, the switch will open and close at the same angular positions during successive operations. We have found that other types of ceramics such as porcelain, Isolantite" or "alsimag under high loads in the presence of the alkaline illl and electric arcs are subjected to an etching action which, in time, will reduce the sharp cutting edge desired and will erode or form a groove in the runway. destroying the operation characteristics of the switch. It is necessary, however, when using an insert of the Alundum type to provide adequate means for dissipatlng the heat from the interior of `the switch by employing a plurality ci' dissipatlng paths other than through the insert. We indicate diagrammatically in Figure 7 the manner in which such heat dissipation can be eoctively secured. Assuming that the point indicated at X is the point at which the heat is generated by arcing between the mercury bodies 02 and l1 at the sharp cutting edge, the heat generated at this point will be transmitted through the body of mercury 82 to the shell or envelope Il, as

indicated by the line I". A portion of the heat u wm also be dissipated by volaauzmon of the vliquid nil. and the carrying away of the heatv by the vapor to the surrounding walls of the envelope, as indicated by the arrows |02. Another portion of the heat will be transmitted through the body of mercury 01, and the metallic electrode 90 directly to the nose portion |00 of Vthe ceramic compression member |01 which is formed of Isolantite or other ceramic of equal heat conductivity, and will pass through the ceramic |01 to vthe envelope as indicated by the line |03 or rearwardlyv out of the Lend of the `switch along theV shank |05 and through the.

, -Figure 4. In the switch shown in Figure 4, however, the terminal washer ||4 has been eliminated and the conductor lead |40 is soldered directly to the compression ring ||2 and the spun-over edge of the envelope. The compression member |01 has the reduced cylindrical portion |42 extending rearwardly along the electrode shank |00', and the shank end and the end of the portion |42 terminate in substantially the same plane. However, the portion |42 is provided with an axial recess |42 about the end of the shank |00fwhich recess is adapted to form an annular space about the end of the shank for receiving the bare end |44 o! the terminal conductor |45. The end |44 is coiled within this recess about the shank, and is soldered thereto in any suitable or desired manner. Over the end of this recess and the end faces of the shank end portion |42 of the member |01 we preferably apply a plastic self-setting cement of the type commercially known as vsauereisen as `indicated at |40. This cement is an electrical resister at extremely high temperatures. running Y up to 2000 F., and upon setting has no water content whatsoever. Further, it is not resoluble in water and consequently provides a waterproof enclosure for the end of the switch. It is capable of adhering firmly to ceramics or refractorles, and forms a good embedment for the leads to relieve tension strains upon the connections of these leads to the electrodes. Iffdesired, the material shown at |46 may be applied 'over the entire end of the switch, taking the place of the material or eement indicated at ||0 in Figure 4. Howe've we ilnd that the case parts ||1 and ||0 can be very effectively cemented together by using ordinary rubber cement, asindieated at |41, and by using such cement, we may also positively seal the notches |24 and |25 about the conductor leads insuch manner that the interior of the .ease members ||1 and ||0 are completely sealed against the entrance of moisture or the like, besides forming a positive bond between the case members preventing their separation. As o re-V suit, the vinterior of the cap member ||0 and the end of the switch may be left open as indicated at |40. and the switch is capable of being operated when immersed inwater or oil, orany simiy l f lar iluid. this operation being enhanced by providing rubber coated leads to the electrodes.`

It is to be understood that the cement as described in connection with Figure may also be employed as an end sealing plastic for any of the embodiments of the invention shown in the present application, and may supplant the use of either Porcelute or green dip where conditions require a dielectric strength; with equally high thermal resistance, and also require that the cement be waterproof.

It will be noted that by employing the tapered surface |00 on the ceramic insert 94, the insert .may be easily withdrawn from the mould due to the draft on this surface, and consequently the danger of cracking or chipping this flange is materially reduced. It is therefore to be understood in connection with the embodiment of the invention shown in Figure 1 that the ceramic shown therein may be of the form 'shown in Figures 4 and 5 with the flange I1 being formed with a tapered external annular surface. This may also be provided for the ceramic 13 of the embodiment shown in Figure 3. Also, the insulating spacing disc 3| of Figure l may be omitted, and the spacing member may be extended outwardly to the end of the shank substantially in the manner shown in Figures 4 and 5, if so desired. This extending portion of the compression member may be either formed separately or as an integral part of the compression disc, as clearly shown by an inspection of Figures 1 and 2.

While ordinarily the switches thus far described are adapted to be operated by tilting the same from a horizontal position in order to provide for movement of the memory contacter toward and away from the electrode or the retained body of mercury for high speed operation, it may be desirable to produce operation of the switch without tilting action. In the switches shown in Figures 2 and 3, this may be readily accomplished by reciprocatory movement of the switch since inertia of the mercury will be sufficient to hold it substantially stationary, and the switch body can be reciprocated to move the electrode into and out of contact with the mercury. However, the other forms of switches having the spunover end and wedge shape type of internal runway may also be operated by reciprocatory longitudinal movement of the switch body, and reference is now made to Figures 8 and 9 disclosing one form of operation mechanism for accomplishing high speed operations of such switches.

Considering these figures in detail, we provide a supporting base member |50 having suitable supporting means |52 adapted to provide a journal for a rotatable shaft |53 extending transversely of the base member |50, and carryingja cam |54 conjointly rotatable with the shaft and having the cam projection |55 adapted to engage a suitable sliding block |50. guided for reeiprocatory movement 'on the base |50 by guide channels or the like (not shown), and is limited against movement in.. one 'direction by the downwardly projecting flange |51 at one-end thereof which engages ,the'end of the- 'I'he block |55 is suitably block |50. Mountedonthe upper surface of the able body of mercury |04 is adapted Vto-xnove to-A consequently the block is shifted rapidly to the position shown in Figure 9. Due to the inertia of the body of mercury l, the switch is driven thereover with the runway |93 serving as a wedge raising the body of mercury I into contact with the retained body |65. The spring |19 biased at opposite ends on pins |12 and |13 carried by the supporting base and the block, respectively, snaps the block |56 back to the position shown in Figure 8 as the cam projection |55 leaves the plate |55.l This results in withdrawal of the wedge from under the body of mercury breaking the contact of the bodies |04 and |85 and openingthe switch` In actual operation the wedge is driven under and withdrawn at high speeds with respect to the body of mercury |94, and little or no longitudinal movement of the mercury is produced, the making and breaking being accomplished by the movement of the wedge beneath the mercury.

Obviously the switch |59 may be any of the types of switches shown in .Figures 1 to 5, inclusive, and the switch shown in Figures 8 and 9 is intended to be representative only of the manner in which such a reciprocating mechanism will be operated in connection with the normal tilting type of switch. A

Reference is now directed to Figure 11 in which we disclose a switch structure indicated generally at |15, and of the general type described in connection with the embodiments of the invention shown in Figures 1 to 5. This structure is provided with the extending electrode shank |15, which preferably is threaded adjacent its end, and which has the ceramic spacing member |11 thereon which may be formed independently of, or as an integral part of the ceramic compression disc |18. Threaded over the projecting end of the shank |18 we provide a supporting bracket which may be of any desired shape and size, and which preferably is provided with an aperture |82 whereby it may be secured to a supporting base. By the provision of such a structure, a mechanical supy port for the switch is provided which can be directly connected to the shank of the electrode, and which is in insulated spaced relation to the metallic envelope. This supporting bracket may be employed for mechanical support, and also for an electrical connection to the shank if so desired, and it is within' the purview of the present invention to provide means for securing the bracket to the shank, either as shown in Figure ll or by using a clamping nut such as the nut 35 of Figure l, or by soldering or welding the bracket directly to the shank when a construction such as shown in Figures 4 or 5 is provided in the switch. It is to be understood that the bracket |80 of Figure ll may be employed in place of the clips |58 of Figures 8 and 9 or/in place of the supporting clips shown in Figure 10- Considering Figure l0 in detail, we provide a supporting base 185, having normally extending end portions |86 adapted to respectively support solenoid members |31 and |88, respectively, having the pole faces |89 and |90. Extending between the ends of the base |85 above the 9,229,251. engage the retained body of mercury |95. The

solenoids m and m are s rdunuty of mais: guide bars Ill adapted to support a carriage |92 for longitudinal sliding movement thereon. The carriage |92 is provided with spaced supporting means |93 adapted to support suitable s metallic envelope type switches |94 and |95. respectively, in opposed relationship. Each of the switches |95 and |95 is provided with the circuit leads and |91, respectively, to the envelope and electrode shank. The carriage |92 is of 1o metallic material, and one terminal of each of, the solenoids |91 and |89 ls connected to the carriage through .flexible electrical connections |98 whereby the carriage is electrically connected between the solenoids and the circuit connected through the conductors |99 to the envelope since the supporting means |98 provides an electrical connection. between the car- .riagevand the envelope.

The other terminal o! the solenoid |01 is con- 20 nected through the conductor |99 to the shank 20| of the switch |95, and the second terminal of the solenoid |90 is connected through the` conductor 292 to the shank 203 of the switch 25 |94.

In the operation of the structure shown in this ligure, the solenoids are alternately energized to produce reciprocatory movement of the carriage |92. Assuming the solenoid |01 to be energized, the pole face |99 thereof actuates the depending 30 armature portion 204 of the carriage, and produces movement of the carriage to the left. This results in driving the wedge portion of the ceramic insert 205 beneath the body of mercury in the switch |94, and as the carriage moves to 35 the left, the mercury 205 is thereby moved into engagement with the retained body of mercury 201. This closes the circuit through the switchA |54 and results in energization of the solenoid |89 through the conductor 202 connected to the electrode shank 203, and through the connection |98 to the carriage. At the same time, the movement of the switch |95 with the carriage res'ilts in breaking of the circuit through the switch |95, the mercury being carried to the outer end of the switch as indicated at 2118, thereby de-energizing the solenoid |81 through disconnection of the mercury from the retained bodyof mercury in contact with the electrode having the projecting shank 200. As a result the armature portion 209 of the carriage is attracted by the pole face 90 of the solenoid |08, and the carriage will be -moved to the right as viewed in Figure 10, whereupon the switch |98 will open and the switch |95 will close, resulting immediately in energization of solenoid |91 to again move the carriage to the left.

Thus the carriage is alternately reciprocated between the solenoids and the switches |94 and |95 are successively opened and closed during each 30 cycle of movement. The circuits controlled by the leads |95 and |91 are consequently also successively opened and closed, and al high speed alternating operation of the switches is thereby produced to operate any suitable mechanism con- 35 trolled by the circuit connections |91 and |05. Such a structure may be used for sign flashing equipment, for automatic feed or control mechanism, for machinery or the like, or in any other application where one circuit is to be closed as 70 the other is opened, and the operations are to i V be accomplished successively at high speeds.

It is therefore believed 'apparent that We have provided certain features of design and construction of the component parts of a switch of this 'Il type which will produce proper heat relationshipswithin theswitchitselfsoastomaintaina cool operating switch even under heavy loads, and which will provide for proper heat dissipal tion in order to maintain the sealing means at high emciency. In addition, the present construe-e tion provides for proper embedment of the terminal leads for the switch in conjunction with suitable radial and axial insulating and spacing l features for preventing dash-overs, and for insuring continued operating performance of the switch forrelatively long periods of time.

In addition, the present construction is peculiarly adapted for high speed operation of both small and large capacity switches of this type, and by suitable control of the liquid illl we are v-able to control the rate of movement of the movable mercury contacter in order to secure precise operation characteristics for the switch.

yWe are aware that various changes in details of the construction are possible, and various minor modiilcatlons may be made in certain constituent parts of the invention. We'thereforel do not intend to be'limited to the precise construction herein shown and described, but only insofar as the invention is dened by the scope and spirit of the appended claims.

We claim:v y

I 1. A mercury switch comprising a metallic cup- 30, shaped envelope having an enlarged end, a ceramic insert in said end having an inclined internal throat. an electrode supported solely by said insert and radially insulated from said eni velope thereby, resilient sealing means enclosing 35 the end face of said insert and said electrode, a. ceramic compression member engaging the outer face of said sealing means and having a tapered portion centered in said sealing means for exerting a radial component of pressure thereon, thel 40' end of said envelope being spunv over to hold said member axially compressed against said sealing means. f 4

2. In combination, a metallic cup-shaped envelope having an enlarged open end, an arc resisting insert of high thermal and alkaline resistance and poor heat conductivity in said end and having `an internal runway terminating in a mercury retaining recess, a body of mercury maintained in said recess, an electrode at the end of said recessv 00' tilizlng under an electric arc', whereby the heat' developed by arcing between said mercury bodies is dissipated outwardly oi the envelope through volatilimtion of said nim and by conduction through said bodies of mercury, said electrode and said compression member.

3. A compression member for a metallic envelope type of mercury switch having an electrode-supporting ceramic insert in one end thereof with resilient sealing means compressed against 'I0 the outer face of said electrode and ceramic, said electrode having a projecting shank portion, comprising a ceramic member of relatively high heat conductivity having an axially extending frustoconical portion centered about said shank within 1g said sealing means and having a radial component vof said ceramic, said insert having a tapered annular shoulder at its outer end spaced radially inwardly of the envelope wall, comprising resilient l5 sealing means having a tapered peripheral flange engaged between said envelope wall and said insert shoulder and having a radial portion fitting against the rear face of said insert and electrode, and central portion of said sealing means being 20 spaced from said shank, and a ceramic compression member centered on said shank and having a forward nose portion disposed radially between said sealing fmeans and said shank, an intermediate disc portion for axially compressing'said 2liA sealing means, and a rear cylindrical portion of reduced diameter about said shank.

5. In a mercury switch of the type in which an electrode is supported solely by a ceramic insert which encloses the` same radially, and resilient sealing means is compressed axially against the end of said ceramic and electrode, means for maintaining the opposite faces of said sealing means at substantially uniform temperature comprising a ceramic compression member of high heat conductivity pressed against the outer faces of said sealing means and said electrode.

6. In combination, in a metal envelope type mercury switch, a ceramic insert of high thermal resistance but low heat conductivity carrying an electrode, said electrode being flush with the 'outer radial surface of said insert and having-a projecting shank of small diameter, resilient sealing means disposed against said radial surface of said insert and electrode about said shank, and a ceramic compression member of high heat conductivity `forced against the outer surface of said sealing means.

'1. An insert for a metallic envelope type of mercury switch Icomprising a ceramic member having a tapered `recess extending axially thereinto from one end thereof and terminating at its smaller end in a plurality of' coaxial annular internal shoulders, one of said shoulders forming a seat for an electrode disc and the other shoulder spacing said disc fromthe small end oisaid recess, and an external frusto-conical surface on said one shoulder disposed radially within the peripheral limits of said insert.

8. In combination, a cup-shaped metallic en- 50 velope having an enlarged end portion joined to the body portion by a frusto-conical section, a ceramic insert adapted to t within said end and having a corresponding frusta-conical section, a tapered recess in the insert terminating in a mercury retaining groove, an electrode disc forming the end wall of said groove and enclosed radially by a'n annular shoulder on said insert, said shoulder having a short external frusta- .m conical surface radially spaced from the inner annular surface of said enlarged end of said envelope.

9. In combination. a cup-shaped metallic envelope having an enlarged end portionjoined to u ceramic insert adaptedto iit within said end and having a corresponding truste-conical section, a tapered recess in the insert terminating in a mercury retaining groove, an electrode disc forming" the end wall of said groove and enclosed radially by an annular shoulder on said insert, said shoulder having a. short external frusto-conical surface radially spaced from the inner annular surface of said enlarged end ot said envelope, and resilient compressible sealing means radially closing the outer face of said disc and said shoulder and having a tapered peripheral flange engaging about said last-named frusto-conical section.

10. A switch comprising a metallic envelope carrying a ceramic insert in its open end, an electrode supported solely by said insert and having a shank projecting axially out of the endoi said envelope, a ceramic compression disc holding said insert in position and having a portion forming an annular cylinder about the shank, the outer 'end face of said cylinder being axially recessed about the end of said shank to form a lead wire receiving recess radially enclosed by said cylinder.

11. A switch comprising a. metallic envelope carrying a ceramic insert in its open end, an electrode supported solely by said insert and having a shank projecting axially out of the end of said envelope, a ceramic compression disc holding said insert in position and havinga portion forming an annular cylinder about the shank, the outer end face oi' said cylinder being axially recessed about the end of said shank to form` a lead wire receiving recess radially enclosed by said cylinder, and cementitious material applied over the end tace of said cylinder and the end o! said shank for embedding the end of said lead wire therein.

12. In combination, a metallic envelope switch having an insert in one end thereof, an electrode supported by the insert and having a shank proiecting outwardly of the end of said envelope, an annular insulating washer on said shank having an axial length such that it projects beyond said envelope, and a supporting bracket secured to the shank and spaced from said envelope by said washer.

13. In combination, a metallic envelope switch 20 having an insert in one end thereof, an electrode supported by the insert and having a shank proiecting outwardly of the end ot said envelope, anV 

